The invention concerns conveyor belts assembled from plastic modules to produce a belt in virtually any length and width. In particular the invention relates to a conveyor belt capable of following a path including both straight and curved sections, and such a belt which has a substantially continuous solid top supporting surface.
Modular plastic conveyor belts, and the modules of which they are constructed, are very well known and the subject of a large number of patents. See, for example, U.S. Pat. Nos. 5,181,601 and 4,742,907, owned by the assignee of the present invention. The belts of both those patents are capable of straight and curving travel, due to the provision of slotted holes in link ends on one side of each module, and elongated interdigited link ends, rendering the ability of module rows to collapse together at the inside of a curve.
Belts having solid, substantially closed conveying surfaces are also very well known. For an example of a modular plastic conveyor belt with a solid conveying surface, see U.S. Pat. No. 5,706,934, also owned by the assignee of the present invention.
Conveyor belts for some specific purposes have included solid conveying surfaces which remain closed when the conveyor traverses a curve. To achieve this, such solid top belts have generally included plates which lap over one another, or lap more deeply over one another on curves, to achieve the required contraction at the inner side of a curve. Examples are the metal conveyors found in baggage handling equipment at airports. An example of such a lap-over structure in a modular conveyor belt is found in patent publication WO93/14010. The components of that belt were disclosed as being either of metal or plastic; the belt modules did not include a multiplicity of interdigited link ends or projections as in the above-referenced patents and as in the present invention described below.
In many applications there is a need for a conveyor belt, having the versatility and practical advantages of modular construction as in the ""601 patent referenced above, and at the same time having a substantially solid or continuous conveying surface without the sometimes objectionable feature of one plate sliding over another which can result in wear and moving edges that can catch or snag conveyed articles.
According to this invention, a plastic modular conveyor belt, of the type described in U.S. Pat. No. 5,181,601, achieves the above stated goals. Such a belt, of the type which is capable of traversing lateral curves, with module rows collapsing together at inner sides of curves, has a solid deck over a central portion, but leaving terminal ends of interdigited projections not covered by the deck structure. The solid decks on each module are above the level of the interdigited projections, such that upon traversing curves the projections toward the inside of the curve can slide under the deck of the adjacent module, and the dimensions of the solid decks are such as to allow the inner sides of the module rows to collapse substantially fully without interference by the edges of the decks, which do not lap over one another.
While traveling through a straight section, the conveyor belt has a gap between succeeding module rows, but this is substantially closed by the interdigited terminal portions of the projections, so that only relatively small objects would be capable of falling through, and such small objects are not carried on the belt.
In some embodiments the edges of the deck structures include longitudinally extending fingers for providing a more continuous load-supporting surface, the fingers becoming more deeply enmeshed in corresponding slots of a succeeding module when the module rows come together at the inside of a curve.
A further embodiment of the invention is for conveyor situations where all curves are in the same direction. In that embodiment, the solid deck or decks making up a module row define a wedge shape, generally trapezoidal, so that on the curves, are all generally of a prescribed radius, the solid deck portions form a truly continuous conveying surface. In straight sections of such a conveyor, the module rows form generally triangular shaped gaps between them, but these are substantially filled by the terminal ends of the interdigited projections at a slightly lower level. Again, interdigited finger structure can be included to provide a more continuous conveying surface in these gaps.
It is thus among the objects of the invention to improve on conveyors capable of traversing straight and curving sections while presenting a substantially closed or continuous conveying surface, by combining the features of interdigited molded plastic conveyor modules with solid deck surfaces covering most of the modules, without the need for plates lapping over one another, therefore providing belts having a substantially continuous top, not completely impervious but sufficiently so for the type of articles to be carried. These and other objects, advantages and features of the invention will be apparent from the following description of a preferred embodiment, considered along with the accompanying drawings.